Hydraulic high-pressure cylinder with rotary piston



April 16, 1968 H. F. w. STEINBACH ETAL 3,

HYDRAULIC HIGH-PRESSURE CYLINDER WITH ROTARY PISTON Filed May 26, 1965 2 Sheets-Sheet l INVENTORS HERMAN/v Fw STE/NBACH WALTHER FGv HEYNEN y Wu Z, ma

Arrorwsvs' April 1968 H. F. w. STEINBACH' ETAL. 3,377,923

HYDRAULIC HIGH-PRESSURE CYLINDER WITH ROTARY PISTON Filed. May 26, 1965 2 Sheets-Sheet z INVENTORS HEHMANN FW STEIINBACH WALTHER F.G.HEYNEN 2, Mb g Mtz A- WR/JEY.

United States Patent 3,377,923 HYDRAULIC HIGH-PRESSURE CYLINDER WITH ROTARY PISTON Hermann F. W. Steinhach, Hohenwartstrasse 24, Marktoberdorf, Germany, and Walther F. G. Heynen, 57 /2 Walkershafen, Kreis, Schwabmunchen, Germany Filed May 26, 1965, Ser. No. 458,852 8 Claims. (Cl. 92-121) The present invention relates to a rotary piston hydraulic high-pressure cylinder and a compression member therefor, and particularly though not exclusively to highpressure cylinders equipped with a partition which is arranged in an axial direction in the cylinder and relatively to which a rotary piston can oscillate, the piston being fixed in an axial direction on a drive or driven shaft which passes through the cylinder.

Hydraulic high-pressure cylinders of the above type comprising a partition and rotary piston are known and are distinguished particularly by the feature that the surfaces of the rotary piston and partition which are acted upon by the fluid pressure are substantially radial to the axis of the shaft and are sealed against the sliding surfaces provided and against their respective supporting surfaces by adjustable lip seals.

One disadvantage of known high-pressure cylinders with rotary pistons is that, owing to the radial arrangement of the surfaces acted upon, both the piston and the partition are subject to a considerable tilting moment, so that the holding members securing them to their respective supporting surfaces are subject not only to shearing stress but to an additional, very high tensile stress caused by the tilting moment resulting from the shearing force. If this tensile stress causes even the slightest expansion of the material of the holdin members, both the piston and the partition are lifted off their supporting surfaces, the seal loses its effectiveness, and the pressure then acting from below further increases the tilting moment, so that the material of the holding members may expand further or break and make the piston seize up.

Another disadvantage of known highpressure cylinders with rotary pistons and adjustable lip seals is that the application pressure of the latter must always be equal to the maximum working pressure arising, so that even if there is only a light load on the apparatus the high frictional resistance of the seals at the sliding surfaces must be overcome. This means that the seals wear out rapidly and need constant adjustment.

The invention aims to avoid these known disadvantages and to provide an improved high-pressure cylinder comprising a partition wall and a rotary piston. This should be simple and cheap to produce, should operate reliably, should have a high degree of efiiciency even if the load fluctuates and, particularly, should have a long life.

In a hydraulic high-pressure cylinder comprising a partition and a rotary piston, wherein the latter is secured to the shaft passing through the center of the cylinder and the former to the inner wall of the cylinder by means of holding members on the respective supporting surfaces, both the piston and the partition being sealed against their supporting surfaces and against the adjacent surfaces which slide past, there is provided, according to the invention, a rotary piston and a partition comprising surfaces being effectively acted upon by pressure, which are inclined at an acute angle to the supporting surface therefor or the adjacent central tangential plane.

As a result of this feature, the pressure on the surfaces which are effectively acted upon is divided into components. One of these is directed to the center line of the shaft in the case of the piston and radially outwardly in the case of the partition, and thus counteracts the tilting moment to which the partition and piston are subject.

In a preferred embodiment of the invention the boundary for the surfaces effectively acted upon by pressure is in the form of seals provided on the piston and partition.

This feature enables the effectively pressurized surfaces to be inclined at an acute angle independently of the embodiment of the piston and partition, through a suitable arrangement of seals on these members.

In this connection, an important feature of the present invention is that, owing to the arrangement of the seals, the piston and partition wall are prismatic with a substantially trapezoidal profile, whereby the wide base surface of the piston lies on the supporting surface of the shaft and the wide base surface of the partition lies on the supporting surface of the inner wall of the cylinder with its profile plane perpendicular to the center line thereof.

The novel design of the piston and partition not only makes it easier to arrange the seals in accordance with the invention, but also provides the great advantage over previous embodiments of increasing the angle through which the piston can be pivoted and thus the usefulness of the apparatus. As a result of the substantial reduction in, or total elimination of, the tilting moments acting on the piston and partition, the respective holding members are subject only to shearing strain and can consequently have a very small cross section. This makes it possible to make the trapezoidal profile of the piston and partition unusually narrow, thus further enlarging the angle of pivoting. It is consequently possible either con siderably to increase the operating pressure without mak ing the apparatus substantially larger than in conventional apparatus, or to decrease the dimensions of the apparatus While retaining the same performance.

In one embodiment, the seals are in theform of selfadjusting round rubber rings or grooved annular sleeves and are mounted on the partition and piston in endless marginal grooves of substantially semi-circular profile. In this way, the seals are only partially exposed to the action of the pressure, so that the profile 0f the seal is deformed in accordance with the pressure components and the profile is pressed resiliently against the piston Wall, partition and sliding walls in dependence on the pressure.

In hydraulic high-pressure cylinders comprising rotary pistons of older type, wherein the piston and partition have trapezoidal profiles and are fixed to the respective supporting surface by their surface opposite to their broad base face, the effectively pressurized surfaces inclined in accordance with the invention may be provided by having the self-adjusting seals plate shaped, with lips arranged against the direction of pressure, and mounted between the sectional surfaces of sections of the piston and partition.

This feature of the invention makes it possible for the tilting moments acting on the piston and partition to be decreased, reversed or totally eliminated in hydraulic high-pressure cylinders with pistons of the older type, without involving a great deal of labor.

The holding members may be either in the form of headed screws screwed into female threads in the bearing surfaces and/or in the form of shearing bushes or shearing pins which are simply mounted in coinciding blind holes in the supporting surface and wide base surface of the piston and partition.

, This last embodiment has the particular advantage that, although the strain is constantly changing, the holding members cannot be moved thereby radially towards the inner wall of the cylinder and damage it.

If the piston and partitions are freed from tilting moment because their effectively pressurized surfaces are suitably inclined, it is even possible for the holding members to be in the form of a key and keyway and to be provided on the supporting surfaces and wide base surfaces of the piston and partition, parallel with the surfaces to be acted upon.

The invention will be further explained with reference to the accompanying drawings. These show preferred embodiments of the invention and, together with the following explanation, disclose further features and advantages thereof. In the drawings:

FIG. 1 is a diagrammatic longitudinal section through a high-pressure cylinder according to the invention comprising a partition and rotary piston,

FIG. 2 is a section taken along the line IIIl in FIG. 1,

FIG. 3 is a diagram showing the position of the surfaces acted upon by pressure,

FIG. 4 is a diagram showing the distribution of pressure on the piston,

FIG. 5 is a diagram showing the distribution of pressure on the partition,

FIG. 6 shows a modified embodiment of the holding members for the piston,

FIG. 7 illustrates the construction and arrangement of annular seals and FIG. 8 shows the arrangement of plate-shaped seals.

The diagrammatic section in FIG. 1 shows the cylinder housing 1 and the cylinder covers 2, which are equipped with suitable pressure-resistance bearings 3 for the shaft 4. Inside the housing 1 and between the cylinder covers 2 the shaft 4 is of enlarged diameter and is equipped with a rotary piston 5, which is secured in position by holding members 6. The piston 5 is in known manner designed as an elongated prism with its end faces curved in a semicircle and is equipped with seals '7 to seal the piston 5 both against its own supporting surface on the shaft 4 and against the walls of the housing 1 and cylinder covers 2 which slide past it.

In the lower portion of the housing 1 a partition 8 is fixed to the inner wall of the housing by holding members 6 and is also sealed against the surface of the shaft 4 which slides past it, against its own supporting surface in the housing 1 and against the cylinder covers 2, by seals 7. Holes 9, ill for the oil supply are provided in the lower part of the housing 1 on both sides of the partition 8, although these could also be provided in the cylinder covers 2 or a hollow shaft 4.

The section in FIG. 2 shows the arangement and design of the piston 5 and partition 8, each of substantially trapezoidal profile.

The piston 5 is secured in position on the supporting surface of the shaft 4 by the holding members 6, and the wide base surface of the partition 8 is secured in position on the supporting surface on the inner wall of the housing 1, again by holding members 6.

FIG. 3 shows how, in the preferred embodiment illustrated, the position of the surfaces effectively acted upon by pressurehereinafter referred to as the thrust surfaces 11 (indicated diagrammatically with dot and dash lines in FIGS. 3 to 7)is unaffected by the shape of the piston 5 and depends exclusively on the position of the seals 7 bounding the thrust surfaces 11 against the shaft 4, the cylinder covers 2 and the inner wall of the housing 1. It will be apparent that under uniform pressure the thrust surface is defined solely by its boundary. The piston 5 could thus have the profile shown in broken lines in FIG. 3, without thereby altering the position of the thrust surfaces 11. However, the preferred profile for the piston 5, which is shown in full lines in FIG. 3, has the advantage not only of enabling the seals 7 to be arranged in a simple manner, but of enabling the pivoting angle of the piston 5 and consequently the general usefulness of the apparatus to be greatly increased as compared with known apparatus having the piston profiles indicated in broken lines in FIG. 3.

For reasons of clarity the lateral contours of the piston ll 5 and partition 8 have been omitted from FIGS. 4 and 5 and only the thust surfaces 11 have been shown. Each of these is inclined at an acute angle 13 to the central tangential plane 12 of the supporting surface for the piston 5 on the shaft 4-. The oil pressure in the direction of the arrow 14, for example on the right hand thrust surface ll, is thereby divided into two components 15, 16. The pressure component 16 gives rise not only to a shearing pressure on the holding members, but also to a tilting moment which is made up of the component 16 and the spacing 17 thereof from the edge It; and which acts in the di ection of the arrow 19. By suitably choosing the angle 13, the opposed torque made up of the component 15 and the spacing 26 thereof from the edge 18 can easily be made to cancel out the torque in the direction of the arrow 19 or even to exceed it and thereby urge the piston 5 against the shaft 4.

The distribution of pressure on the partition 8 is illustrated diagrammatically in FIG. 5. It will be seen that the oil pressure in the direction of the arrow 14 is also divided into the components I5, 15, and that the torque in the direction of the arrow 19 about the edge 20 of the partition, made up of the component 16 and the spacing 21 thereof from the edge 26, is cancelled out by the opposed torque of the component 15. If the angle of inclination of the thrust surfaces 11 is suitably chosen, the opposed torque in the direction of the component 15 may even be made large enough to urge the partition 8 radially against the inner wall of the housing 1, so that instead of the holding members having to be in the form of headed screws 23 as in FIG. 5, shearing bushes o-r shearing pins 24 mounted in blind holes 25 may be used as in FIG. 4. There is a danger, particularly in the case of the piston 5, that the constant changes in strain may cause holding members in the form of head-ed screws 23 to move radially towards the inner wall of the housing 1 and to damage the housing by scraping it, whereas the shearing bushes or pins 2 are secured against radial displacement.

As shown in FIG. 6, the holding members may be in the form of a keyway and key 26, 27, provided on the supporting surfaces of the shaft 4 and housing 1 and on the wide base surfaces of the piston 5 and partition 8, respectively, parallel to the thrust surfaces 11.

FIG. 7 shows a preferred embodiment of the selfadjusting seals '7, in which they are in the form of round rubber rings 28 provided in endless marginal grooves 29 in the piston 5 and partition 8, respectively.

The oil pressure in the direction of the arrow 14 is divided by the resilient round rubber rings 29 into two components 3% 31 which, in dependence on the amount of pressure in the direction of the arrow 14 urge the resilient round rubber ring 28 both against the inner wall of the housing l and against the inner wall of the semicircular marginal groove 29. This not only seals the piston 5' and partition 8 in a pressure resistant manner against their own supporting surfaces and the surfaces which slide past, but also reduces the frictional resistance as the operating pressure drops. It will be seen from the individual figures that the endless marginal grooves 29 are provided immediately adjacent and parallel to the thrust surfaces 11, in the adjoining prismatic surfaces 32 of the piston 5 and partition 3. Apart from the special advantage of eliminating all tilting moments on the piston 5 and partition 8, if these components of a hydraulic highpressure cylinder are constructed and arranged in accordance with the invention, their assembly will be greatly simplified and expedited.

FIG. 8 shows a means of increasing or totally eliminating the tilting moment in accordance with the invention in the case of a piston "5 and likewise a partition, of conventional profile. In such a case, it is an advantage to use plate-shaped seals 33 with lips 34 arranged against the direction of pressure, and for the seals to be provided between the sectional surfaces of portions 35 of the piston 5. With such an arrangement the surfaces effectively acted upon by pressure coincide with the plate-shaped seals 33, so that the tilting moment is reduced or totally eliminated in accordance with the invention. I

What we claim is:

1. A fluid operable system comprising: a cylinder, a rotor rotatably mounted in said cylinder in radially spaced relationship thereto, a partition mounted in and extending in axial direction of said cylinder, a vane engaging said rotor along a circumferential surface portion and extending in axial direction of said rotor, means for detachably connecting said vane to said rotor and passing through said surface portion, said partition and said vane together with said cylinder and said rotor confining chamber means adapted to be subjected to a fluid under pressure, first and second sealing means mounted in said vane on opposite sides of a plane through the centers of said vane and of said rotor for sealing engagement with said cylinder and said rotor, said first and second sealing means having surfaces freely exposed to a fluid under pressure in said chamber means, said first and second sealing means being located in planes converging radially outwardly and being respectively inclined at such an angle with respect to a plane tangential 'to said rotor through said connecting means that the resultant force of the fluid under pressure acting on said vane passes through said circumferential surface portion -to thereby subject said connecting means substantially to shearing forces only and that no tilting moment exists about the respective lines of intersection between said converging planes and said circumferential surface portion.

2. A system according to claim 1, in which said vane is provided with a first and a second endles circumferential groove on opposite sides of said plane through said centers and respectively located in said radially outwardly converging planes, and in which said first and second sealing means are respectively self-adjustingly arranged in said first and second groove.

3. A system according to claim 1, in which said vane comprises a plurality of sections, and in which said first and second sealing means are interposed between adjacent sections and include lips forming said freely exposed surfaces and located in said radially outwardly converging planes.

4. A system according to claim 1, in which said vane and said rotor include aligned passages and in which said connecting means include a shearing pin arranged in said aligned passages.

5. A system according to claim 1, in which said rotor and said vane are provided with a cooperating key and keyway forming said connecting means.

6. A system according to claim 1, in which said vane is prismatic and has a substantially trapezoidal cross section in planes perpendicular to the longitudinal axis of said rotor with the larger one of the parallel sides of said vane engaging said rotor.

7. A system according to claim 1, in which said first and second sealing means respectively include a first seal and a second seal extending in longitudinal direction of said vane for respective sealing engagement with said cylinder and said rotor.

8. A fluid operable system comprising: a cylinder, a

rotor rotatably mounted in said cylinder in radially spaced relationship thereto, a partition engaging said cylinder along a first circumferential surface portion and extending in axial direction of said rotor, a vane engaging said rotor along a second circumferential surface portion and extending in axial direction of said rotor, first means for detachably connecting said vane to said rotor and passing through said second surface portion, second means for detachably connecting said partition to said cylinder, said partition and said vane together with said cylinder and said rotor confining chamber means adapted to be subjected to a fluid under pressure, first and second sealing means mounted in said vane on opposite sides of a plane through the centers of said vane and of said rotor for sealing engagement with said cylinder and said rotor, said first and second sealing means having surfaces freely exposed to a fluid under pressure in said chamber means, said first and second sealing means being located in planes converging radially outwardly and being respectively inclined at such an angle with respect to a plane tangential to said rotor through said first connecting means that the resultant force of the fluid under pressure acting on said vane passes through said second circumferential surface portion to thereby subject said first connecting means substantially to shearing forces only and that no tilting moment exists about the respective lines of intersection between said converging planes and said second circumferential surface portion, said partition having third and fourth sealing means mounted in said partition on opposite sides of a plane through the centers of said partition and of said cylinder for sealing engagement with said cylinder and said rotor, said third and fourth sealing means having surfaces freely exposed to a fluid under pressure in said chamber means, said third and fourth sealing means being located in planes converging radially inwardly and being respectively inclined at such an angle with respect to a plane tangential to said cylinder through said second connecting means that the resultant force of the fluid under pressure acting on said partition passes through the first circumferential surface between said partition and said cylinder to thereby subject said second connecting means substantially to shearing forces only and that no tilting moment exists about the respective lines of intersection of said radially inwardly converging planes and said first circumferential surface.

References Cited UNITED STATES PATENTS 540,492 6/ 1895 Humes 92-122 2,540,903 2/1951 Moushey et a1. 92-125 2,633,105 3/1953 Lasater 92125 2,811,142 10/ 1957 Shafer 92-122 2,870,748 1/1959 Hemphi ll 92125 3,181,437 5/1965 Rumsey et al. 92123 FOREIGN PATENTS 572,797 11/ 1958 Belgium.

MARTIN P. SCHWADRON, Primary Examiner.

I. C. COHEN, Assistant Examiner. 

1. A FLUID OPERABLE SYSTEM COMPRISING: A CYLINDER, A ROTOR ROTATABLY MOUNTED IN SAID CYLINDER IN RADIALLY SPACED RELATIONSHIP THERETO, A PARTITION MOUNTED IN AND EXTENDING IN AXIAL DIRECTION OF SAID CYLINDER, A VANE ENGAGING SAID ROTOR ALONG A CIRCUMFERENTIAL SURFACE PORTION AND EXTENDING IN AXIAL DIRECTION OF SAID ROTOR, MEANS FOR DETACHABLY CONNECTING SAID VANE TO SAID ROTOR AND PASSING THROUGH SAID SURFACE PORTION, SAID PARTITION AND SAID VANE TOGETHER WITH SAID CYLINDER AND SAID ROTOR CONFINING CHAMBER MEANS ADAPTED TO BE SUBJECTED TO A FLUID UNDER PRESSURE, FIRST AND SECOND SEALING MEANS MOUNTED IN SAID VANE ON OPPOSITE SIDES OF A PLANE THROUGH THE CENTERS OF SAID VANE AND OF SAID ROTOR FOR SEALING ENGAGEMENT WITH SAID CYLINDER AND SAID ROTOR, SAID FIRST AND SECOND SEALING MEANS 